Meegalla R. Chandraratne

By Meegalla R. Chandraratne and Asfaw G. Daful

The chapter focuses on recent trends of biomass conversion into valuable energy, chemicals, gaseous and liquid fuels. Biomass is presently the largest source of renewable energy and the primary bioenergy resource in the world. A comprehensive discussion on different types, sources and compositions of biomass is presented. The most abundant biomass on the earth is lignocellulose and it represents a major carbon source for chemical compounds and biofuels. The chapter presents a thorough review of lignocellulosic biomass and the importance of biomass as a renewable source. It then reviews biomass classification and composition. It introduces the analysis of biomass feedstock. Biomass is converted to energy, chemicals and clean fuels using various conversion techniques such as thermochemical, chemical and biochemical. The chapter provides a thorough examination of thermochemical conversion processes that use high temperatures to break down the bonds of organic matter. It briefly introduces combustion and gasification, followed by a comprehensive review of different pyrolysis techniques.

Part of the book: Recent Perspectives in Pyrolysis Research

By Meegalla R. Chandraratne and Asfaw Gezae Daful

This chapter provides an overview of current efforts and advances as well as environmental and economic aspects of fast pyrolysis and hydrothermal processing, which are potential technologies for bioenergy production, mainly bio-oil and syngas. Biomass is presently the primary bioenergy resource in the world. The chapter presents a brief discussion of sources and compositions of biomass. Biomass is converted to various products using thermochemical conversions. Pyrolysis is a thermochemical process that converts biomass into carbon-rich solid residue, condensable vapors, and non-condensable gases in the absence of oxygen. It is a promising technology for converting biomass into renewable biofuels with environmental and economic advantages. Pyrolysis processes are classified based on their operating conditions and desired products. Two thermochemical processes, fast pyrolysis and hydrothermal processing are reviewed. Fast pyrolysis produces a higher quantity and quality of bio-oil and syngas than slow and intermediate pyrolysis processes. Hydrothermal processing converts wet biomass into carbonaceous biofuel. The ability to produce higher-value bioenergy by these pyrolysis technologies depends on the feedstock and operating condition of the pyrolysis processes. This chapter will present the most promising features of fast pyrolysis and hydrothermal processing along with their optimal pyrolysis conditions in maximizing the production of biofuels.

Part of the book: Biomass, Biorefineries and Bioeconomy

By Meegalla R. Chandraratne and Asfaw Gezae Daful

The high moisture content poses a major technical barrier to using wet biomasses in thermochemical conversions. Hydrothermal conversions open efficient ways to convert wet biomass into carbonaceous products as an alternative to thermochemical methods such as pyrolysis, gasification, and combustion. Three types of hydrothermal conversions, hydrothermal carbonization (HTC), hydrothermal liquefaction (HTL), and hydrothermal gasification (HTG), use different operating conditions to convert wet biomass into distinct products: solid (hydrochar), liquid (aqueous soluble bio-oil), and gaseous fractions. Water plays a dominant role in hydrothermal conversions. HTC uses relatively mild conditions. HTL and HTG use subcritical and supercritical conditions, respectively. Conversion mechanisms and the effect of process parameters are also discussed in detail. The solid product hydrochar (HC) has properties comparable to biochar and activated carbon, hence a range of potential applications. Current and emerging applications of HC, including energy production and storage, soil amendment, wastewater treatment, carbon capture, adsorbent, and catalyst support, are discussed.

Part of the book: From Biomass to Biobased Products [Working title]

By Asfaw Gezae Daful, Marie Loridon and Meegalla R. Chandraratne

This chapter presents bio-based lactic acid production process from lignocellulosic biomass. Bio-based chemicals can replace the chemicals that we usually get from petroleum-based resources, and they are used to produce cleaners, solvents, adhesives, paints, plastics, textiles, and many other products. Lactic acid is one of such candidates of bio-based chemicals with important applications in various industrial sectors such as the chemical, pharmaceutical, food, and cosmetics industries, where its demand is steadily increasing. It is also an essential building block for numerous commodity and intermediate-biobased chemicals making it as a suitable alternative to their fossil-derived counterparts. The bioconversion process of transforming lignocellulosic biomass into lactic acid consists of four primary stages. Initially, pretreatment is performed to enable the utilization of all C5 and C6 sugars by the selected microorganism. These sugars are then hydrolyzed and fermented by a suitable microorganism to produce either L- or D-lactic acid, depending on the desired stereochemistry. Finally, the lactic acid is separated and purified from the fermentation broth to obtain a purified product. The promising method for the industrial production of bio-based lactic acid will be of continuous simultaneous saccharification and fermentation in a gypsum-free process using Mg(OH)2 as neutralizer, followed by reactive distillation for purified lactic acid production. The cradle-to-gate life cycle assessment model for the biobased lactic acid production process indicated that the about 80–99% of the environmental burdens of most of the environmental impact categories can be reduced compared with its equivalent fossil-based lactic acid, making biobased lactic acid environmentally superior to the fossil-based lactic acid.

Part of the book: From Biomass to Biobased Products [Working title]